Presentation on theme: "MEASUREMENT AND INSTRUMENTATION"— Presentation transcript:
1MEASUREMENT AND INSTRUMENTATION R.HARIHARANLecturer/EEE
2UNIT - 4 STORAGE AND DISPLAY DEVICES Magnetic disk and tape Recorders digital plottersPrintersCRT displaydigital CROLEDLCDdot matrix display.
3RecordersA recorders records electrical and non electrical quantities as a function of time.They are used for having permanent records. It monitors continuously the condition state or value of the process variable such as flow, force, pressure, temperature, current , voltage, electrical power etc.Current and voltage can be recorded directly while the non electrical quantities are recorded indirectly by first converting them to equivalent currents or voltages with the help of sensors or transducers.
5Magnetic Tape and Disc Recorders Magnetic tapes and magnetic discs are essentially storage devices. A magnetic tape is a thin dimensionally stable plastic coated with iron oxide particles one side.Mechanism-The magnetic tapes or disc passes under the gap, and the oxide particles retain a state of permanent magnetization proportional to the flux existing at that instant , the particle leaves the gap.
6Basic Components of Tape recorder Recording HeadMagnetic HeadReproducing HeadTape transport mechanismConditioning device.
7Methods Of Magnetic Tape recording Direct RecordingFM recordingPulse Duration Modulation Recording
11Cathode Ray Oscilloscope (CRO) The cathode ray oscilloscope is a versatile laboratory instrument used for display, measurement and analysis of waveform.CRO are very fast X-Y plotter displaying an input signal versus another signal or versus time.The Stylus of this plotter is a luminous spot which moves over the display area in response to an input voltage.
14The luminous spot is produced by a beam of electrons striking a fluorescent screen. Applications of CROSampling oscilloscopes.Storage oscilloscopes.An analog oscilloscope.Cathode ray tube (CRT)Electron gun assembly.Deflection plate assembly.Fluorescent screen.Glass envelope.Base through which connection are made to various parts.
15LEDIt is perhaps the most important of the display device for use in instrumentation systems.It is a PN junction device that emits light when a current passes through it in the forward direction.Charge carrier recombination occurs at PN junction as electrons from N side recombines with holes on P side.
16Conti..When this happens ,charge carrier give up energy in the form of heat and light.If the semiconductor material is translucent the light is emitted and junction is source of light.Charge carrier recombination takes place in the P type material. For maximum light emission a metal film anode is deposited around edge of P Type material.
17LCDUsed in application of display of numeric and alpha numeric characters in dot matrix and segmental displays.TypesDynamic scattering typeField effect type.